These cores are the SA1 composition with boron (1-5%), iron (85-95%), and silicon (5-10%).[2]

(photo by the author.)

Metallic glasses closely resemble metals, so they don't possess the transparency that makes most glass valuable. There's a wide range of transparent glass compositions, each developed to serve a particular function. These functions can be as simple as window glazing, or as technically advanced as conductive glass for computer and cellphonedisplays. The following table gives a few examples of transparent glass compositions.

The amorphous tantalum yttrium oxide is formed by the addition of a small amount of yttrium oxide (Y2O3) to tantalum oxide (Ta2O5). Tantalum oxide is widely used as a high refractive index material since it's a thermally stable oxide with high optical transmissivity.[3] While tantalum oxide has a 300°C higher crystallization and glass-transition temperature than other high refractive index oxides such as titanium oxide (TiO2) and hafnium oxide (HfO2), it's still not stable at the 800 °C oxygen anneal required for magneto-optical garnet crystallization. It's only after such crystallization that these garnets exhibit high Faraday rotation.[3]

Crystallization is sometimes suppressed by adding elements of a smaller ionic radius to a host material. For example, the crystallization temperature of HfO2 is increased when La2O3 is added, lanthanum being larger than hafnium.[3] To suppress the crystallization of Ta2O5, the larger yttrium ion in the form of Y2O3 can be added.[3] This was the approach taken in the current study with the addition of about 14% Y2O3, which was enough to increase the crystallization temperature to about 850°C.[4]

"We used amorphous tantalum yttrium oxide to form a dielectric mirror and combined it with magnetic garnet. Actually, other than magnetic garnet, there are more materials that have not been combined with dielectric mirrors because of the high-temperature thermal treatment that is required. I hope that our findings will help make such materials usable too."[4]